Defrag and erase files and programs that
you don't need. Or copy them to disk if you don't want to throw them away but don't need them on your comp. (obvious)
If you have any programs that you used temporarily uninstall them!! Of course you know all this. Move all of the text files and photos and random crap to the external and keep only the programs on C. Anytime you need to save an item save it to your external and just use the C to run your programs. You can create a shortcut to your external hard drive to your desktop which makes things easier to move....and keep organized.
You won't be able to defrag to reorganize your files until you have at least 15 percent of free space to work with!!...Unless things have changed...So burn files, move them, or throw them away if you don't want them.
Or just listen to someone that knows what in the hell they are talking about....
That's what I did.......